Powdered activated carbon coupled with enhanced coagulation for natural organic matter removal and disinfection by-product control: Application in a Western Australian water treatment plant

The removal of organic precursors of disinfection by-products (DBPs), i.e. natural organic matter (NOM), prior to disinfection and distribution is considered as the most effective approach to minimise the formation of DBPs. This study investigated the impact of the addition of powdered activated carbon (PAC) to an enhanced coagulation treatment process at an existing water treatment plant on the efficiency of NOM removal, the disinfection behaviour of the treated water, and the water quality in the distribution system. This is the first comprehensive assessment of the efficacy of plant-scale application of PAC combined with enhanced coagulation on an Australian source water. As a result of the PAC addition, the removal of NOM improved by 70%, which led to a significant reduction (80–95%) in the formation of DBPs. The water quality in the distribution system also improved, indicated by lower concentrations of DBPs in the distribution system and better maintenance of disinfectant residual at the extremities of the distribution system.The efficacy of the PAC treatment for NOM removal was shown to be a function of the characteristics of the NOM and the quality of the source water, as well as the PAC dose. PAC treatment did not have the capacity to remove bromide ion, resulting in the formation of more brominated DBPs. Since brominated DBPs have been found to be more toxic than their chlorinated analogues, their preferential formation upon PAC addition must be considered, especially in source waters containing high concentrations of bromide

Impact of NOM character on copper adsorption by trace ferric hydroxide from iron corrosion in water supply system

The fate of trace concentrations of cupric sulfate (<0.4 mg/L) dosed into chloraminated distribution systems to inhibit nitrification has been shown in this study to be controlled by at least two crucial factors: the character of natural organic matter (NOM) and iron hydroxide corrosion products present at low concentrations (<2 mg/L). This research quantified the removal of Cu(II) ions added into waters containing trace Fe(OH)3 flocs and the effect of NOM of different character on this removal. The dominant dissolved copper species in NOM-containing waters were found to be Cu(II)–NOM complexes. Both intramolecular chelation and intermolecular complexation can occur, with the latter occurring preferentially and resulting in the aggregation of smaller organic molecules to form larger molecules. The presence of ferric hydroxide flocs when Cu(II) ions were added into NOM-containing waters was shown to result in removal of Cu(II) ions, presumably as Cu(II)–NOM complexes. This removal was through adsorption processes obeying Freundlich isotherms, although the presence of larger NOM molecules and heterogeneous copper species (e.g. Cu(OH)2(s) and CuO(s)) appeared to shield smaller Cu(II)–NOM complexes from adsorption to some extent. For the strategy of inhibition of nitrification in distribution systems by the addition of Cu(II) ions, complexation of Cu(II) ions by NOM and adsorption of Cu(II)–NOM complexes by ferric hydroxide flocs released from pipe walls pose significant operational challenges to maintaining the concentration of Cu(II) ions through the distribution system

Analysis of free amino acids in natural waters by liquid chromatography-tandem mass spectrometry

This paper reports a new analytical method for the analysis of 18 amino acids in natural waters using solid-phase extraction (SPE) followed by liquid chromatography-electrospray tandem mass spectrometry (LC–MS/MS) operated in multiple reaction monitoring mode. Two different preconcentration methods, solid-phase extraction and concentration under reduced pressure, were tested in development of this method. Although concentration under reduced pressure provided better recoveries and method limits of detection for amino acids in ultrapure water, SPE was a more suitable extraction method for real samples due to the lower matrix effects for this method. Even though the strong cation exchange resin used in SPE method introduced exogenous matrix interferences into the sample extracts (inorganic salt originating from the acid–base reaction during the elution step), the SPE method still incorporates a broad sample clean-up and minimised endogenous matrix effects by reducing interferences originating from real water samples. The method limits of quantification (MLQ) for the SPE LC–MS/MS method in ultrapure water ranged from 0.1 to 100 μg L−1 as N for the different amino acids. The MLQs of the early eluting amino acids were limited by the presence of matrix interfering species, such as inorganic salts in natural water samples. The SPE LC–MS/MS method was successfully applied to the analysis of amino acids in 3 different drinking water source waters: the average total free amino acid content in these waters was found to be 19 μg L−1 as N, while among the 18 amino acids analysed, the most abundant amino acids were found to be tyrosine, leucine and isoleucine

KEGIATAN MENUMBUHKAN JIWA KEPEMIMPINAN PADA ANAK MELALUI EDUKASI DIGITAL DI YAYASAN DOMYADHU LEBAK BULUS

Tujuan dilaksanakannya PKM ini untuk memberikan pengetahuan kepada anak-anak agar mereka bias lebih termotivasi untuk lebih disiplin kreatif dan mandiri dalam menumbuhkan jiwa kepemimpinan melalui edukasi digital. Sikap disiplin sendiri kapan memunculkan sikap mandiri dan kreatif dimana anak-anak akan mampu mengatasi berbagai macam masalah yang dihadapi sehingga menumbuhkan jiwa kepemimpinan itu sendiri. Metode yang dipakai dalam PKM ini adalah metode presentasi dimana bertujuan agar pemahaman tentang penumbuhan jiwa kepemimpinan ini mudah diterima oleh anak-anak. Dan hasil dari PKM ini kami berharap anak- anak dapat lebih paham mengenai definisi kepemimpinan dan melihatcontoh orang sekitar yang bias dijadikan sosok pemimpin supaya mereka lebih mengerti seperti apa sosok pemimpin itu sendiri sehingga mereka tahu bahwa jiwa kepemimpinan sangat penting diterapkan dan bisa dimulai pada kegiatan sehari-hari

Analysis of halonitriles in drinking water using solid-phase microextraction and gas chromatography–mass spectrometry

Halonitriles are a class of nitrogen-containing disinfection by-products (DBPs) that have been reported to be more toxic and carcinogenic than the regulated DBPs. While haloacetonitriles (HANs) are often measured in drinking waters, there is little information on the formation, characteristics, and occurrence of other, higher molecular weight halonitriles. Halopropionitriles and halobutyronitriles have been predicted to be highly toxic and carcinogenic, and may have sufficient potency and selectivity to account for epidemiological associations of chlorinated and chloraminated water with adverse health effects. This paper reports on the development, optimisation, and validation of a simple, robust, and sensitive analytical method for the determination of halonitriles in waters, as well as the application of the method to study the formation and characteristics of halonitriles. This is the first reported method development for analysis halopropionitriles and halobutyronitriles, and the first study on their formation and occurrence as DBPs in drinking waters. The new method uses headspace solid-phase microextraction to extract the halonitriles from water, which are then analysed using gas chromatography–mass spectrometry (HS SPME/GC–S)

The formation of halogen-specific TOX from chlorination and chloramination of natural organic matter isolates

The formation of disinfection by-products (DBPS) is a public health concern. An important way to evaluate the presence of DBPs is in terms of the total organic halogen (TOX), which can be further specified into total organic chlorine (TOCl), bromine (TOBr), and iodine (TOI). The formation and distribution of halogen-specific TOX during chlorination and chloramination of natural organic matter (NOM) isolates in the presence of bromide and iodide ions were studied. As expected, chloramination produced significantly less TOX than chlorination. TOM was the dominant species formed in both chlorination and chloramination. TOI was always produced in chloramination, but not in chlorination when high chlorine dose was used, due to the limited presence of HOI in chlorination as a result of the oxidation of iodide to iodate in the presence of excess chlorine. The formation of TOI during chloramination increased as the initial iodide ion concentration increased, with a maximum of similar to 60% of the initial iodide ion becoming incorporated into NOM. Iodine incorporation in NOM was consistently higher than bromine incorporation, demonstrating that the competitive reactions between bromine and iodine species in chloramination favoured the formation of HOI and thus TOI, rather than TOBr. Correlations between the aromatic character of the NOM isolates (SUVA(254) and % aromatic C) and the concentrations of overall TOX and halogen-specific TOX in chloramination were observed. This indicates that the aromatic moieties in NOM, as indicated by SUVA(254) and % aromatic C, play an important role in the formation of overall TOX and halogen-specific TOX in chloramination. THMs comprised only a fraction of TOX, up to 7% in chloramination and up to 47% in chlorination. Although chloramine produces less TOX than chlorine, it formed proportionally more non-THM DBPs than chlorine. These non-THM DBPs are mostly unknown, corresponding to unknown health risks. Considering the higher potential for formation of iodinated DBPs and unknown DBPs associated with the use of chloramine, water utilities need to carefully balance the risks and benefits of using chloramine as an alternative disinfectant to chlorine in order to satisfy guideline values for THMs